Place bacon in a large skillet and cook over medium-high heat, turning occasionally, until evenly browned, about 10 minutes. Drain bacon slices on paper towels and crumble. Reserve drippings in the skillet.

Cook and stir cabbage and onion in bacon drippings over medium-high heat until cabbage begins to wilt, 1 to 2 minutes. Stir bacon, salt, and pepper into cabbage mixture; cook until cabbage is wilted, 3 to 5 minutes more.

Stir kielbasa into cabbage mixture and reduce heat to low. Cover the skillet and simmer until cabbage is lightly golden and tender, about 1 hour.